Here is the full list of all 35 Avernum: Escape From the Pit achievements.
Discover 10 locations of interest.
Purge a nefarious infiltrator from Silvar's sewers.
Slay 100 foes.
Open a secret door.
Escape the tunnels under Fort Avernum.
Learn a mage spell at level 3.
Learn 6 mage spells at level 3.
Learn 18 mage spells at level 3.
Learn a priest spell at level 3.
Learn 6 priest spells at level 3.
Learn 18 priest spells at level 3.
Get a dread curse. Then cure it.
Slay 1000 foes.
Dig up 5 caches.
Dig up 40 caches.
Have ten potions made.
Have fifty potions made.
Discover 50 locations of interest.
Find the secret at the bottom of Lost Bahssikava.
Sss-Thsss will trouble Avernum no longer.
Steal the treasure from Gremlin's Gold.
The mayor of Formello lost something of great value. Recover it.
Purge a certain powerful demon from the Tower of Magi. Phew. Hope they stay out of trouble in the future.
Find something that lets you fly.
Reform a legendary blade from Avernum's past.
Join the Scimitar.
Meet the Archmage Erika.
Enter the Castle at last.
Avernum has five dragons. See if you can whittle that down a bit.
Destroy the demon Grah-Hoth, making Avernum safe from his menace at last.
Discover a route back to the surface world. There must be one somewhere.
Deliver harsh vengeance to the cruel tyrant who sent the Avernites into the underworld.
Complete all three game-winning quests in Avernum and never set the difficulty below Normal.
Complete all three game-winning quests in Avernum and never set the difficulty below Hard.
Complete all three game-winning quests in Avernum and never set the difficulty below Torment.